| Scientific production management in the field is the main measure to increase crop yield. This study on the basis of predecessors’ work and ours, in view of the problem of water and fertilizer resources sustainable utilization during the dryland wheat yield formation, through the methods of combining field experiment and data mining. Studied the contribution of photosynthetic characteristics and nutrient distribution to yield of wheat lines(cultivar) and the relationship among them under conventional tillage; clarified dynamic changes of grain-filling parameters during wheat yield formation; quantitative evaluated the influences of different mulching and tillage on wheat yield, water use efficiency(WUE) and agronomic traits; and analyzed the yield-increasing effect of dryland wheat under different production measures and soil nutrient. To provide references for the consruction of dryland wheat production management system in different regions, and provide scientific basis for improving the wheat yield and WUE synergistically. The main results are as follows:(1)The study found that the average photosynthetic rates(Pn) were not significant between the large-spike lines and control cultivar during the jointing, heading, flowering, pre-ripening and mid-ripening period in the field experiment. However, the average PSII maximum energy conversion efficiency(Fv/Fm), PSII actual quantum efficiency(ФPSⅡ), Photochemical quenching coefficient(qP), PSII reaction center activity(Fv’/Fm’) and leaf real-time water-use efficiency of the large-spike lines were 1.0, 5.1, 3.6, 0.8, and 43.4%, respectively, higher than those of control. The assimilates and nitrogen(N) distribution proportions in different tissues was ranked in the order of grains > culms + sheathes > rachis + glumes > flag leaves > penultimate leaves > remain leaves. To provide theoretical basis for the construction of high yield population and rational utilization of nutrients in the large spike wheat lines.(2)The results showed that the average yield, grain number per spike(GNE), kernel weight per spike and 1000-kernel weight(TKW) of the large-spike lines were 16.0, 26.8, 42.6 and 15.4%, respectively, significantly higher than those of control cultivar in the field experiment for two years. The TKW of the upper, middle and basal parts of the spike experienced a ‘slow-fast-slow’ pattern of growth from flowering to maturity. The big-spike lines had greater dry matter accumulations than the control cultivar 46 days after flowering, and also had higher kernel-filling rates in the basal part of the spike during the late growth period and greater kernel weights in the middle part of the spike throughout the entire kernel-filling process. The kernel-filling rates of the different parts of the spike during the three kernel-filling stages were ranked in the order of V2(rapidly increasing kernel-filling stage) > V3(slowly increasing kernel-filling stage) > V1(moderately increasing kernel-filling stage). Therefore, the plumpness, size and weight of kernels produced by the big-spike lines can likely be increased by increasing the kernel-filling duration during the late kernel-filling stage.(3)The effects of different mulching methods on wheat yield under different drought condition were studied by Meta-analysis technology. The main results of the study were that: The effect sizes of the mulching practices were ranked in the order of RFM(Ridge-furrow mulching) > MTMC(mulching with two materials combined) > MOM(mulching with other materials) > WSM(Wheat Straw mulching) > FM(Flat mulching); the effect sizes of the mulching practices at the different precipitations during the growth period of wheat were ranked in the order of(< 150 mm) >(> 250 mm) >(150–250 mm); the effect sizes of the mulching practices in the different regions were ranked in the order of Henan > Shanxi > Shaanxi > Gansu; WSM, MTMC and FM performed better in improving the yield of wheat at the rainfalls of < 150 mm, 150–250 mm, and > 250 mm during the growing season, respectively; the yield of wheat with FM, MTMC, MOM and MOM were higher than those with the other mulching practices in Shaanxi, Gansu, Henan and Shanxi; the yield of wheat with RFM was 27.4% higher than that with FM, indicating that RFM appeared to be the most effective practice to improve the yield of wheat among all the practices.(4)The effects of different mulching and tillage methods on wheat yield and WUE were studied by Meta-analysis technology. This synthesis suggests that wheat yield was in the range of 259–7898 kg·hm-2 for FM and RFM. The sequence of WUE effect sizes was similar to that of wheat yield for the practices. Wheat yields were more sensitive to soil water at planting covered by plastic film, wheat straw, liquid film, water-permeable plastic film and sand compared to no tillage, subsoiling tillage and rotational tillage(RT). RFM and RT increased the yields of wheat by 18 and 15%, respectively, and corresponding for WUE by 20.11 and 12.50%. This synthesis demonstrates that RFM was better for avoiding the risk of reduced production due to lack of precipitation; however, under conditions of better soil moisture, RT and MTMC were also economic.(5)The effects of different production methods on wheat yield under different soil fertility levels were studied by Meta-analysis technology. The results were as follows:Mulching and tillage increased grain yield by 13.20 and 7.83% relative to that from conventional tillage, respectively, and the increase due to mulching was 47% greater than that due to tillage; Grain yield, the number of spikes per hectare, and GNE were markedly affected by N at 200–285 kg·ha-1; Application of N affected grain yield nearly three times more than mulching combined with tillage did, the effect of N being evident mainly in the number of spikes and the number of grains and that of mulching and tillage, albeit slight, in the main agronomic traits; Soil organic matter 10–15 g·kg-1, total N 1–1.5 g·kg-1, available phosphorus 10–20 mg·kg-1, and available potassium at 100–200 mg·kg-1 showed significant positive effects on grain yield in the rainfed farmland and can be regarded as optimal levels—thereby proving that wheat yields can be increased substantially and sustainably without any adverse effects on the environment by production practices. |
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